Investigations of solid liquid interfaces in ultra-thin liquid films via single particle tracking of silica particles

Single particle tracking with a wide field microscope is used to study the solid liquid interface between the viscous liquid tetrakis(2 ethylhexoxy)-silane and a silicon dioxide surface. Silicon dioxide nanoparticles (5 nm diameter) marked with the fluorescent dye rhodamine 6G are used as probes. The distributions of diffusion coefficients, obtained by mean squared displacements, reveal heterogeneities with at least two underlying diffusion components. Measurements on films with varying film thicknesses show that the slower component is independent of the film thickness, while the faster one increases with the film thickness. Additionally, we could show that the diffusion behavior of the particles cannot be sufficiently described by only two diffusion coefficients

Electrochemical properties of carbon nanoparticles entrapped in silica matrix

Carbon-based electrode materials have been widely used for many years for electrochemical charge storage, energy generation, and catalysis. We have developed an electrode material with high specific capacitance by entrapping graphite nanoparticles into a sol gel network. Films from the resulting colloidal suspensions were highly porous due to the removal of the entrapped organic solvents from sol-gel matrix giving rise to high Brunauer-Emmett-Teller (BET) specific surface areas (654 m2/g)and a high capacitance density (∼37 F/g). An exponential increase of capacitance was observed with decreasing scan rates in cyclic voltammetry studies on these films suggesting the presence of pores ranging from micro (< 2 nm) to mesopores. BET surface analysis and scanning electron microscope images of these films also confirmed the presence of the micropores as well as mesopores. A steep drop in the double layer capacitance with polar electrolytes was observed when the films were rendered hydrophilic upon exposure to a mild oxygen plasma. We propose a model whereby the microporous hydrophobic sol-gel matrix perturbs the hydration of ions which moves ions closer to the graphite nanoparticles and consequently increase the capacitance of the film.This work was supported by the National Institutes of Health grant NS048826

Development and characterization of fluorescent dye-doped nanoparticles with enhanced fluorescence intensity and photostability [abstract]

Nanoscience Poster SessionWe report the development of fluorescent dye doped organosilicate nanoparticles (DOSNPs) synthesized from poly-methylsilsesquioxane(PMSSQ), resulting in high fluorescence intensity and excellent photostability. The surface modified DOSNPs have hydrophilic surfaces and hydrophobic cores that enhance water-solubility and protect the dyes from oxidation and phtobleaching. These DOSNPs show superior properties over conventional dyes such as high fluorescence intensity due to approximately hundred dye molecules per particle and photostability demonstrating 7% and 76% fluorescence decay under continuous excitation for rhodamine 6G (R6G) DOSNP and R6G molecules, respectively, and have potential to be used in many areas, for example, imaging, sensing and solar cells. DOSNPs, when conjugated to anti-fibronectin antibodies, increased sensitivity of detection by approximately 600 fold relative to individual dye molecules conjugated to antibody. The DOSNPs are being applied to the development of diagnostic devices to be used in the detection of drugs, metabolites and pathogens

Organosilicate nanoparticles and its applications in chem-biosensors, electronics, multifunctional coatings and textiles

This invention reports a novel technique for the rapid and cost-efficient synthesis of organosilicate nanoparticles (OSNPs) that have been successfully applied as individual building blocks for various applications. Doping these nanoparticles with fluorescent dyes results in highly fluorescent, biocompatible, water soluble nanoparticles with demonstrated long term photostability and with surface groups that can be readily used to attach various biological moieties. Fluorescent intensity of dye doped OSNPs (22.4 ± 5.3 nm) is shown to be 200 times brighter with 94% of the initial fluorescence intensity retained than the constituent dyes under continuous excitation for 10 minutes. In contrast, under identical test conditions, individual dye molecules retained only 58% of the initial fluorescence demonstrating that these nanoparticles have excellent utility in lifesciences research, forensics, chemical - biological sensors and biological imaging applications. Through our patented technology of novel bottom up fabrication technique, these nanoparticles have been used to fabricate highly porous transparent films. Optically smooth hydrophobic films with low refractive indices (as low as 1.048) and high surface areas (as high as 1325 m2/g) can be achieved on large area substrates. These unique materials can be readily interfaced with existing immunoassays in the form of inexpensive dip-stick assays for the sensitive detection of chemical and biological warfare agents or novel diagnostic strips for point of care applications. Our preliminary evaluation of these coatings in combination with dye doped OSNPs for construction of diagnostic immunoassays gave ~180 fold enhancement in fluorescence signal enhancement compared to traditional (microscope glass slide and fluorescent dye molecules) based assays. OSNPs used as filler elements within sol-gel based coatings have been shown to greatly enhance their structural stability, flexibility and wear resistance. Crack-free coatings (with thicknesses exceeding 30 microns)/novel multifunctional electrospun fibers have been successfully achieved by employing OSNP fillers (up to 75% by weight) within sol-gel compositions. POTENTIAL AREAS OF APPLICATIONS: *Chemical Biological sensors *Medical Diagnostics *Multifunctional coatings *Next generation Chemical-Biological protection textiles (Soldier technologies) PATENT STATUS: Non provisional patent application on file INVENTOR(S): Sangho Bok; Venumadhav Korampally; Luis Polo-Parada; Vamsi Mamidi; Keshab Gangopadhyay; William R. Folk; Purnendu K. Dasgupta and Shubhra Gangopadhyay CONTACT INFO: Wayne McDaniel, Ph.D.; [email protected] ; 573-884-330

Ultrasensitive detection of lipoarabinomannan with plasmonic grating biosensors in clinical samples of HIV negative patients with tuberculosis.

BACKGROUND:Timely diagnosis of tuberculosis disease is critical for positive patient outcomes, yet potentially millions go undiagnosed or unreported each year. Sputum is widely used as the testing input, but limited by its complexity, heterogeneity, and sourcing problems. Finding methods to interrogate noninvasive, non-sputum clinical specimens is indispensable to improving access to tuberculosis diagnosis and care. In this work, economical plasmonic gratings were used to analyze tuberculosis biomarker lipoarabinomannan (LAM) from clinical urine samples by single molecule fluorescence assay (FLISA) and compared with gold standard sputum GeneXpert MTB/ RIF, culture, and reference ELISA testing results. METHODS AND FINDINGS:In this study, twenty sputum and urine sample sets were selected retrospectively from a repository of HIV-negative patient samples collected before initiation of anti-tuberculosis therapy. GeneXpert MTB/RIF and culture testing of patient sputum confirmed the presence or absence of pulmonary tuberculosis while all patient urines were reference ELISA LAM-negative. Plasmonic gratings produced by low-cost soft lithography were bound with anti-LAM capture antibody, incubated with patient urine samples, and biotinylated detection antibody. Fluorescently labeled streptavidin revealed single molecule emission by epifluorescence microscope. Using a 1 fg/mL baseline for limit of detection, single molecule FLISA demonstrated good qualitative agreement with gold standard tests on 19 of 20 patients, including accurately predicting the gold-standard-negative patients, while one gold-standard-positive patient produced no observable LAM in urine. CONCLUSIONS:Single molecule FLISA by plasmonic grating demonstrated the ability to quantify tuberculosis LAM from complex urine samples of patients from a high endemic setting with negligible interference from the complex media itself. Moreover, agreement with patient diagnoses by gold standard testing suggests that single molecule FLISA could be used as a highly sensitive test to diagnose tuberculosis noninvasively

Shock Wave Based Cell Transfection and Fluorescent Organosilicate Nanoparticles for Targeted Drug Delivery [abstract]

Nanoscience Poster SessionNanotechnology is a multidisciplinary field that has applications in life sciences, alternative energy, national defense, and electronics. In the field of medicine, nanotechnology may enable intelligent drug delivery using multifunctional nanoparticles. Here, we show two technologies that are envisioned to work in tandem to enable targeted detection and treatment. First, a shock wave generator used for cell transfection and drug/particle delivery is presented. Then, fluorescent dye/drug encapsulated organosilicate nanoparticles (OSNP) with functionalized surfaces for targeted delivery are described. The shock wave generator has been successfully used to deliver various molecules and nanoparticle to inside of the cells with very high efficiency and low cell damage. These include dextran (77 kDa), naked plasmid, and dye-doped organosilicate nanoparticles into several types of cells lines including T47-D, HL-60, and MCF-7, and also into tissues including entire chicken heart (at developmental stage 20-30) and chicken spinal cord. Dye doped organosilicate nanoparticle surfaces conjugated to antibodies have been successfully used in immunofluorescence assays. Close examination of the nanostructure of these particles reveal its unique nanoporous structure. These nanoparticles are currently under investigation for drug encapsulation and sustained release. The implication of these technologies is that the OSNP can be used as targeted drug carriers, and the shock wave generator can be used to deliver the OSNP into cells to which the particles attach. The research on shock wave micro-transfector system has been funded by the National Science Foundation Grant Opportunities for Academic Liason with Industries program

Sensor Organosilicate Nanoparticles for Diagnostic Devices and Environmental Devices

Information in this entry was gathered from http://tmir.missouri.edu/mte2011/Technology.htmlThis invention reports a novel technique for the rapid and cost-efficient synthesis of organosilicate nanoparticles (OSNPs) that have been successfully applied as individual building blocks for various applications. Through our patented technology of novel bottom up fabrication technique, these nanoparticles have been used to fabricate highly porous transparent films. Optically smooth hydrophobic films with low refractive indices (as low as 1.048) and high surface areas (as high as 1325 m2/g) can be achieved on large area substrates. These films have been studied and used for a solid phase microextraction (SPME) membrane for identification and quantification of polychlorobiphenyls (PCBs) for replacement of polydimethylsiloxane (PDMS) membranes which are surrently used to detect PCBs in underground water. Furthermore, doping these nanoparticles with fluorescent dyes results in highly fluorescent, biocompatible and water soluble nanoparticles with demonstrated long term photostability and with surface groups that can be readily used to attach various biological moieties. Fluorescent intensity of dye-doped OSNPs (22.4 ± 5.3 nm) is shown to be 200 times brighter than the constituent dyes. These unique materials can be readily interfaced with existing immunoassays in the form of inexpensive dip-stick assays for the novel diagnostic strips for point of care applications. Our preliminary evaluation of these films in combination with dye-doped OSNPs for construction of diagnostic immunoassays gave ~180 fold enhancement in fluorescence signal enhancement compared to traditional (microscope glass slide and fluorescent dye molecules) based assays. Potential Areas of Applications: Diagnosis of CNS diseases, Monitor the efficacy of treatment of CNS disease, Estimate the degree of CNS tumor growth, Measure progression of clinical and preclinical pathologies in drug trials, Surgery guidance. Patent Status: U.S. Patent 7,907,809. Inventor(s): Shubhra Gangopadhyay, Keshab Gangopadhyay, Venumadhav Korampally, Sangho Bok. This presentation was an elevator pitch at the Missouri Technology Expo 2011

Synthesis and characterization of nanostructures and their applications : from supercapacitors to fluorescent labels to proteins

Title from PDF of title page (University of Missouri--Columbia, viewed on October 21, 2010).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Dissertation advisor: Dr. William Folk and Dr. Shubhra Gangopadhyay.Vita.Ph. D. University of Missouri--Columbia 2010.[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Nanomaterials have gained importance in virtually all fields from industrial applications to pure science research since these were developed. However, synthesis and characterization of these nanomaterials are not trivial nor fully understood. This thesis focuses on the synthesis and characterization of nanostructures/nanomaterials and their applications. First, properties of nanostructures prepared with sol-gel chemistry and carbon based materials leading to supercapacitors with unique hydrophobic/hydrophilic structure have been studied. Second, fluorescent dye-doped nanoparticles prepared from organosilicate polymers, poly-methylsilsesquioxane (PMSSQ), as small as 3.5nm and as large as 50nm, have been synthesized which exhibit very intense fluorescence as well as excellent photo-stability. Surface modified nanoparticles were used for conjugation with proteins. The conjugated nanoparticle-protein complexes have been characterized with respect to the number of dye molecules per protein, biological activity and sensitivity of detection of ligands. Third, specificity and sensitivity of the nanoparticle-protein complexes in immunofluorescence assays have been used to image fibronectin in chick heart, resulting in three orders of magnitude enhancement of detection compared to commercial dye-labeled antibody. Finally, progress in the development of a dipstick assay for detection of corticosteroid binding globulin (CBG) bound to cortisol has been achieved, which will be used for a simple and robust diagnostic device being able to measure the ratio of cortisol to 6[beta]-hydroxycortisol as an in vivo indicator of induction of an enzyme, cytochrome P450 3A4 (CYP3A4).Includes bibliographical reference

Regional Traffic Event Detection Using Data Crowdsourcing

Accurate detection and state analysis of traffic flows are essential for effectively reconstructing traffic flows and reducing the risk of severe injury and fatality. For this reason, several studies have proposed crowdsourcing to resolve traffic problems, in which drivers provide real-time traffic information using mobile devices to monitor traffic conditions. Using data collected via crowdsourcing for traffic event detection has advantages in terms of improved accuracy and reduced time and cost. In this paper, we propose a technique that employs crowdsourcing to collect traffic-related data for detecting events that influence traffic. The proposed technique uses various machine-learning methods to accurately identify events and location information. Therefore, it can resolve problems typically encountered with conventionally provided location information, such as broadly defined locations or inaccurate location information. The proposed technique has advantages in terms of reducing time and cost while increasing accuracy. Performance evaluations also demonstrated its validity and effectiveness

Investigations of solid liquid interfaces in ultra-thin liquid films via single particle tracking of silica particles

Single particle tracking with a wide field microscope is used to study the solid liquid interface between the viscous liquid tetrakis(2 ethylhexoxy)-silane and a silicon dioxide surface. Silicon dioxide nanoparticles (5 nm diameter) marked with the fluorescent dye rhodamine 6G are used as probes. The distributions of diffusion coefficients, obtained by mean squared displacements, reveal heterogeneities with at least two underlying diffusion components. Measurements on films with varying film thicknesses show that the slower component is independent of the film thickness, while the faster one increases with the film thickness. Additionally, we could show that the diffusion behavior of the particles cannot be sufficiently described by only two diffusion coefficients